In this blog post, we’ll explore how small errors that can occur during protein synthesis affect life and why cells strictly regulate this process.
Proteins are among the most important substances that make up our bodies. They play a key role not only in muscle formation but also in the composition of hair, skin, and nails. However, the role of proteins goes beyond simply building the body’s structure. Various substances essential for sustaining life—such as hormones, enzymes, and antibodies—are also made of proteins. Hormones help various organs in the body communicate with one another, while enzymes catalyze the countless chemical reactions that occur within the body. Antibodies, meanwhile, protect the body from invading viruses and bacteria. As such, proteins are involved in nearly all activities of living organisms and are absolutely essential for our bodies to function normally.
So where exactly are these proteins made, and how? Let’s take a closer look inside the cell to find the answer.
To cook a dish called “protein,” you first need a recipe. This recipe is DNA. DNA is a molecule that stores genetic information and is housed within the cell nucleus. It contains instructions on which proteins to produce and what structures those proteins should have. Therefore, DNA is often called the “blueprint of life.” Cells use this blueprint to produce the proteins they need and maintain their vital functions.
Now, the cell must locate the blueprint for the protein it needs. However, because DNA is such a crucial original document, it is not directly transported outside the cell nucleus. This is because if the original were damaged, it could cause serious problems for the entire organism. Therefore, the cell creates a copy of a specific portion of the DNA. This copy is messenger RNA, or mRNA.
The process by which information from DNA is copied onto mRNA is called transcription. This process occurs with great precision. Cells utilize various correction mechanisms to minimize errors that may occur during the copying process. Nevertheless, some errors can still occur, and if these errors accumulate, they can lead to disease or aging. The completed mRNA carries the genetic information contained in the DNA out of the cell nucleus and into the cytoplasm.
Now, the actual process of protein synthesis begins.
In the cytoplasm, there are small structures called ribosomes. Ribosomes are essentially factories that produce proteins. When mRNA arrives at a ribosome, it begins to read the information encoded within it. Transfer RNA (tRNA) plays a crucial role in this process.
tRNA is responsible for transporting amino acids, which are the building blocks of proteins. The proteins in our bodies are made by combining twenty different types of amino acids, and each tRNA carries one specific amino acid. The ribosome reads the code recorded on the mRNA in sequence, and the tRNA accurately supplies the corresponding amino acids.
At the same time, rRNA—a key component of the ribosome—acts as a catalyst, linking one amino acid to another. This process is called translation. As translation proceeds, amino acids are linked together to form a long chain, eventually resulting in a single polypeptide chain. This process continues until a stop signal encoded in the mRNA is encountered.
Upon reaching the stop signal, the polypeptide chain is released from the ribosome. However, this does not immediately mean that the protein is complete. The newly formed chain must first adopt a three-dimensional structure capable of performing its function.
Proteins are not simply linear strands. Polypeptide chains fold into specific shapes through hydrogen bonds and various chemical interactions. First, secondary structures—such as helical or fan-like structures—are formed, and subsequently, the chain folds into a more complex tertiary structure. In some cases, multiple proteins bind together to form a quaternary structure.
According to recent research, the process by which proteins fold correctly is far more complex than previously thought. Special proteins called chaperones exist within cells to help newly synthesized proteins fold into their correct shapes. If a protein folds incorrectly, the cell either corrects it or breaks it down and removes it. Thanks to this quality control system, most proteins are able to function normally.
So what happens if an error occurs during protein synthesis?
Although living organisms are equipped with highly sophisticated correction systems, they cannot completely prevent all errors. Mutations may occur in DNA, errors may arise during transcription, or incorrect amino acids may be incorporated during translation. Additionally, proteins may fold incorrectly.
Most errors are corrected or eliminated by the cell itself. However, if an error in a critical gene goes uncorrected, it can lead to serious consequences. Since proteins are key elements that determine a cell’s structure and function, even a single small mistake can have a major impact on the cell’s overall biological activity.
A prime example is sickle cell anemia. This disease begins with a single base change in the gene that produces hemoglobin, the protein responsible for transporting oxygen in the blood. Although it is merely a difference of a single letter, this change alters the structure of the hemoglobin protein, causing red blood cells to take on a sickle-like shape. These deformed red blood cells cannot pass smoothly through blood vessels, and their ability to supply oxygen is reduced. Ultimately, this leads to problems such as anemia, pain, and organ damage.
Recently, it has been discovered that errors in protein synthesis and abnormal protein folding are also linked to degenerative brain diseases such as Alzheimer’s and Parkinson’s. Furthermore, mRNA vaccines—which gained widespread attention during the COVID-19 pandemic—are a prime example of technology that utilizes the principles of protein synthesis. Scientists are developing new technologies to prevent and treat diseases by harnessing the process by which cells produce proteins.
Furthermore, artificial intelligence (AI) technology is ushering in a new era of protein research. While it used to take years to determine the three-dimensional structure of a protein, today AI predicts protein structures, significantly accelerating new drug development and disease research. This demonstrates that protein research is evolving beyond simple basic biology to become a core field in future medicine and the biotechnology industry.
Protein synthesis is, as such, an astonishingly intricate process. Information stored in DNA is transmitted to mRNA; amino acids are linked together in the ribosome; and the completed chain folds into a precise structure to become a functional protein. Mechanisms for detecting and correcting errors exist throughout this process, and it is thanks to these systems that living organisms can survive stably.
Ultimately, the reason we can breathe, move, and think healthily is because countless proteins are being produced with precision within our cells. Protein synthesis can be considered one of the most fundamental yet most marvelous processes that sustain life.
